//! 数据库填充模块

#[cfg(feature = "database")]
use sqlx::{Database, Pool};
use serde_json::Value;
use crate::error::{DataForgeError, Result};
use crate::generation::DataForge;

/// 数据库适配器 Trait
pub trait DatabaseAdapter {
    /// 自动推断表结构
    fn infer_schema(&self) -> Result<TableSchema>;
    
    /// 批量数据插入（支持事务回滚）
    fn bulk_insert(&self, table: &str, data: Vec<Value>) -> Result<usize>;
    
    /// 类型转换系统
    fn type_mapping(&self, rust_type: &str) -> String;
}

/// 表结构定义
#[derive(Debug, Clone)]
pub struct TableSchema {
    pub name: String,
    pub fields: Vec<FieldSchema>,
}

/// 字段结构定义
#[derive(Debug, Clone)]
pub struct FieldSchema {
    pub name: String,
    pub field_type: String,
    pub nullable: bool,
    pub default_value: Option<String>,
}

/// 数据库填充器
pub struct DatabaseForge {
    forge: DataForge,
    connection_string: String,
    batch_size: usize,
}

impl DatabaseForge {
    /// 创建新的数据库填充器
    pub fn new(connection_string: &str) -> Self {
        Self {
            forge: DataForge::default(),
            connection_string: connection_string.to_string(),
            batch_size: 1000,
        }
    }

    /// 设置批次大小
    pub fn batch_size(mut self, size: usize) -> Self {
        self.batch_size = size;
        self
    }

    /// 配置表填充
    pub fn table<F>(self, table_name: &str, count: usize, config: F) -> TableFillConfig
    where
        F: FnOnce(&mut TableBuilder) -> &mut TableBuilder,
    {
        let mut builder = TableBuilder::new(table_name.to_string());
        config(&mut builder);
        
        TableFillConfig {
            forge: self,
            table_name: table_name.to_string(),
            count,
            fields: builder.fields,
        }
    }
}

/// 表填充配置
pub struct TableFillConfig {
    forge: DatabaseForge,
    table_name: String,
    count: usize,
    fields: Vec<(String, Box<dyn Fn() -> Value + Send + Sync>)>,
}

impl TableFillConfig {
    /// 执行填充
    #[cfg(feature = "database")]
    pub async fn fill(self) -> Result<usize> {
        // 这里应该实现实际的数据库连接和插入逻辑
        // 由于这是示例，我们只返回模拟结果
        println!("模拟填充表 {} 共 {} 条记录", self.table_name, self.count);
        
        // 生成示例数据
        for i in 0..self.count.min(5) { // 只打印前5条作为示例
            let mut record = serde_json::Map::new();
            for (field_name, generator) in &self.fields {
                record.insert(field_name.clone(), generator());
            }
            println!("记录 {}: {}", i + 1, serde_json::to_string_pretty(&record)?);
        }
        
        Ok(self.count)
    }

    /// 同步版本的填充（不需要database feature）
    pub fn fill_sync(self) -> Result<usize> {
        println!("模拟填充表 {} 共 {} 条记录", self.table_name, self.count);
        
        // 生成示例数据
        for i in 0..self.count.min(5) { // 只打印前5条作为示例
            let mut record = serde_json::Map::new();
            for (field_name, generator) in &self.fields {
                record.insert(field_name.clone(), generator());
            }
            println!("记录 {}: {}", i + 1, serde_json::to_string_pretty(&record)?);
        }
        
        Ok(self.count)
    }
}

/// 表构建器
pub struct TableBuilder {
    table_name: String,
    fields: Vec<(String, Box<dyn Fn() -> Value + Send + Sync>)>,
}

impl TableBuilder {
    fn new(table_name: String) -> Self {
        Self {
            table_name,
            fields: Vec::new(),
        }
    }

    /// 添加字段
    pub fn field<F>(&mut self, name: &str, generator: F) -> &mut Self
    where
        F: Fn() -> Value + Send + Sync + 'static,
    {
        self.fields.push((name.to_string(), Box::new(generator)));
        self
    }
}